JPH05222148A - Heat-resistant resin dust - Google Patents

Abstract

PURPOSE:To produce a heat-resistant friction dust for a friction material which effectively functions at room temperature to a high temperature above 350 deg.C. CONSTITUTION:A heat-resistant resin dust is prepared by mixing a novolac epoxy resin modified with an aromatic hydrocarbon resin with a cyanic ester curable resin composition mainly consisting of a monofunctional or polyfunctional cyanic ester, a prepolymer of this ester or a prepolymer (a) of this ester with an amine or both (a) and a monofunctional or polyfunctional maleimide, a prepolymer of this maleimide or prepolymer (b) with this maleimide with an amine and a layered inorganic substance, curing the mixture, and grinding the cured product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant friction dust for friction materials, which functions effectively even at room temperature to high temperatures exceeding 350 ° C.

[0002]

2. Description of the Related Art Conventionally, as friction dust for organic friction materials, cashew-nut shell oil, formalin resin using drying oil, and rubbers such as natural rubber and SBR are used as relatively inexpensive ones. It was being done. However, these are inferior in heat resistance, and lack in mechanical strength during heating, upper limit temperature of use and the like.

For example, rubber-based dust obtained by reheating old tires or other carbon-containing rubber and crushing it has a heating weight loss onset temperature of about 150 to 200 ° C., which is a 10% weight loss index used in this field as a heat resistance index. The temperature is about 200-230 ℃. In addition, in a high temperature state, there is a disadvantage that it becomes pitch-like and the friction coefficient is greatly reduced.

Next, the most used cashew
Resin dust has a 10% weight loss temperature in air of 260 to 300 ℃
Pyrolyzes at about 520-550 ℃, and the residual carbon ratio after decomposition is extremely low. In addition, like the rubber type, it sometimes decomposes through a pitch state at a temperature of about 280 ° C, which may significantly reduce the friction coefficient, which is a major drawback from the viewpoint of safety. In addition, since a strongly acidic compound is usually used as a catalyst in the production of cashew / resin dust, there is a drawback in that this remains and the metal-based filler and the like are easily corroded.

In addition, a semi-metallic material using steel fiber as a substitute fiber from a conventional friction agent using asbestos as a reinforcing base material and phenol resin as a binding resin.
It is known that non-asbestos type tisk brake pads that mainly use type, aramid fiber, and carbon fiber make a distinctive squeaking noise during braking.

[0006]

As described above, the heat-resistant resin dust, which has solved the problems of the conventional resin dust, is surprisingly obtained by using a cyanate ester-based epoxy resin (I) modified with an aromatic hydrocarbon resin. Curable resin composition (II)
In addition, the layered inorganic material (III) is blended, and the final curing temperature 2
What was cured at 00 ℃ or higher, 10% weight loss temperature is 320 ℃
As described above, without passing through the liquid state, having a high carbonization rate,
Even at 400 ° C, it maintains a friction coefficient almost the same as 100 ° C,
Moreover, they have found that they exhibit a high friction coefficient even at room temperature. As a result, for example, when used as a disc brake pad, it reduces brake squeal sufficiently, withstands high temperatures at high speeds and maintains a sufficient friction coefficient, and has excellent fade resistance and wear resistance. The present invention has been completed by discovering that they can be manufactured.

[0007]

That is, the present invention provides an aromatic hydrocarbon resin-modified novolac type epoxy resin (I).
And (a) a monofunctional or polyfunctional cyanate ester, the cyanate ester prepolymer or a prepolymer of the cyanate ester and an amine, or (a) and (b) a monofunctional or polyfunctional Cyanate ester-based curable resin composition containing maleimide, the maleimide prepolymer, or the maleimide and amine prepolymer as a main component
(II) and the layered inorganic material (III) are mixed, cured at a final curing temperature of 200 ° C. or higher, and pulverized to obtain a heat-resistant resin dust. The amount of the cyanate ester-based curable resin composition (II) is usually 50% by weight or less, preferably 10% by weight or less.
Is 40% by weight, and the compounding amount of the layered inorganic substance (III) is 5 to 100 parts by weight based on 100 parts by weight of the total of the components (I) and (II).
It is 60 parts by weight, and particularly, the layered inorganic substance (III) is heat resistant resin dust which is synthetic mica or hexagonal boron nitride.

The present invention will be described below. Aromatic hydrocarbon resin-modified novolac type epoxy resin of the present invention (I)
Is obtained by reacting an aromatic hydrocarbon resin, phenols and formaldehyde to obtain an aromatic hydrocarbon resin-modified novolac, and reacting this -OH group with epichlorohydrin to epoxidize it.

Here, as the epoxy resin, an epoxy resin derived from bisphenol A, phenol novolac, cresol novolac, etc. is generally used. However, when a bisphenol A type epoxy resin is used in place of the aromatic hydrocarbon resin-modified novolac type epoxy resin (I) of the present invention, the heat resistance is poor, the tackiness occurs at high temperatures, and the friction coefficient becomes unstable. However, it cannot be used due to the large amount of wear. Further, novolac type epoxy resin made of phenol or cresol cannot be used because it is hard and brittle.

As the aromatic hydrocarbon resin as a raw material, mesitylene, xylene, toluene, benzene, naphthalene,
One of various other aromatic hydrocarbons is used as a raw material, or a mixture of two or more thereof is used, and examples thereof include mesitylene resin, xylene resin, toluene resin, benzene resin, and naphthalene resin. Also, as phenols,
Examples include phenol, cresol, xylenol, resorcinol and the like. Any formaldehyde can be used as long as it generates formaldehyde under reaction conditions. Furthermore, the method using epichlorohydrin is the most convenient and preferable for the reaction with the epoxy resin.

The aromatic hydrocarbon resin-modified novolak is obtained by mixing the above-mentioned aromatic hydrocarbon resin and phenol with an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, an acidic catalyst such as toluenesulfonic acid, xylenesulfonic acid or oxalic acid, or acetic acid. A method of reacting with a neutral catalyst such as calcium, magnesium acetate, zinc acetate, or other organic acid metal salt and then reacting with formaldehyde can be mentioned. After reacting phenols with formaldehyde, aromatic compounds can be used. It can also be carried out by a method of reacting with a hydrocarbon resin or a method of simultaneously reacting with an aromatic hydrocarbon resin, phenols and formaldehyde. Incidentally, it is preferable not to use hexamethylenetetramine which is usually used as a curing agent.

The ratio of the aromatic hydrocarbon resin to the phenols is preferably approximately the same as the reactive group equivalent of the phenol which is usually used in the aromatic hydrocarbon resin used, and the reaction. Examples of the functional group include -CH ₂ -OH
_{, -CH 2 -O-CH 2 -} , -CH 2 -O-, the oxygen-containing groups such as -CH ₂ -O-CH ₂ -OH are exemplified. If the amount of phenols is too small, part of the reaction product may gel, which may cause inconveniences such as viscosity increase and unreacted substances remaining due to interruption of the reaction. The coefficient of friction becomes unstable at high temperatures. Further, formaldehyde is also set to such a degree as to cause a novolak reaction.

For example, when a xylene resin (= xylene formaldehyde resin) having a number average molecular weight of 350 to 800 and an oxygen content of 8 to 17% by weight is used and reacted with phenol, xylene resin / phenol = 100/100 ~ 250 (weight ratio), preferably 100 / 100-200. The aromatic hydrocarbon resin-modified novolac obtained by this method is usually a brown solid having a melting point of 60 to 100 ° C.

The phenolic hydroxyl group in the novolak modified with an aromatic hydrocarbon resin is reacted with epichlorohydrin,
Epoxidation gives an aromatic hydrocarbon resin-modified novolac epoxy resin. The reaction can be carried out by a known method, and the obtained epoxy resin usually has a melting point of 45 ° C or higher.

The cyanate-based curable resin composition (II) of the present invention comprises (a) a monofunctional or polyfunctional cyanate ester, a cyanate ester prepolymer or a cyanate ester and an amine. The prepolymer is an essential component, and from the aspect of imparting heat resistance, etc. (b)
A monofunctional or polyfunctional maleimide, the maleimide prepolymer, or the prepolymer of the maleimide and an amine, and the epoxy resin (c) are appropriately mixed and used from the viewpoint of workability.

Cyanato resin (a) is disclosed in Japanese Examined Patent Publication No. 41-1928.
No. 45-11712, No. 44-1222, German Patent No. 119018
No. 4, USP-4026913, -4022755, -3448079, -3553244, -3755
402, -3740348, -3595900, -3694410, -4116946 and the like, and (a) + (b) or (a) + (b) + (c) cyanate ester-maleimide resin and cyanic acid. Ester-
Maleimide-epoxy resins are known from JP-B-54-30440, JP-B-52-31279, USP-4110364, etc., and (a) + (c) cyanate ester-epoxy resins are JP-B-46-41112. No.

When the maleimide component (b) is used in the cyanate ester-based curable resin composition (II) of the present invention, the amount thereof is usually 80% by weight or less of the resin component in the composition (II), preferably Is 30 to 60% by weight, and when an epoxy resin is used, it is preferable to use a trifunctional or higher functional one, usually 30% or less of the resin component in the composition (II), preferably 2 to 10% by weight. %. Furthermore, it is preferable that the component (a) is the main component.

Examples of the layered inorganic substance (III) of the present invention include flake powders such as mica, talc, graphite, h-BN (= hexagonal boron nitride) and needle powders. The average particle diameter is in the range of 0.1 to 300 μm, but 1.0 to 200 μm is preferable in the application of the present invention. Among them, mica (= mica) is preferable, and fluorine such as muscovite (muscovite), phlogovite (phlogopite) and biotite (biotite), which are natural minerals of aluminum silicate, are fluorinated. Examples thereof include synthetic mica and synthetic mica. In the present invention, it is preferable to use a product obtained by drying and removing water. Especially, when using natural mica, it is necessary to dry the product at about 250 ° C. for 1 hour or more to remove the water. is there.

The above-mentioned aromatic hydrocarbon resin-modified novolac epoxy resin (I) is added with a cyanate ester type curable resin composition (II) in an amount of usually 50% by weight or less, preferably 10 to 40%.
Wt%, layered inorganic (III) total amount of (I) and (II) 1
A known curing catalyst of component (I) or (II) is added in an amount of 5 to 60 parts by weight, preferably 8 to 40 parts by weight with respect to 00 parts by weight, and the mixture is usually melt-mixed and reacted. The curing reaction proceeds so that heat can be easily removed, and the final curing temperature is 200 ° C.
After being cured as described above, it is pulverized to produce the heat resistant resin dust of the present invention.

As the curing catalyst of the component (I) which is optionally used, an aliphatic or aromatic amine, imidazole,
Phenol novolac resins and the like are preferable, and as the curing catalyst of the component (II), organic metal salts (including metal chelate compounds), inorganic metal salts, organic peroxides and the like are preferable. In particular, an organic metal salt alone or a combination system of an organic metal salt and an organic peroxide can be mentioned.
Examples of the organic metal salt include zinc naphthenate, lead stearate, lead naphthenate, zinc octylate, tin oleate, tin octylate, dibutyltin maleate, manganese naphthenate, cobalt tethenate, acetylacetone manganese, and the like. Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, capryl peroxide, acetyl peroxide, parachlorobenzoyl peroxide, and di-tert-butyl-di-perphthalate. The amount of these curing catalysts used is in the range of the amount of catalyst in a general sense, and for example, it is used in an amount of 0.01 to 5% by weight based on the total resin components in the composition.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following examples. In addition, "part" and "%" in Examples and the like are based on weight unless otherwise specified. Example 1 Xylene-formaldehyde resin (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name; Nikanol H, number average molecular weight 460-500)
, Oxygen content 10-11%) 100 parts and 120 parts phenol, 0.1 part paratoluenesulfonic acid as a catalyst, 130 ℃
And reacted for 2 hours. Then 1 part zinc acetate dihydrate
40 parts of 37% formalin was added and reacted at 100 ° C for 3 hours. After that, it is dehydrated under reduced pressure while heating, and the temperature is 150 ° C.
At that point, dehydration under reduced pressure was terminated to obtain a xylene resin-modified novolak phenol resin having a melting point of 80 ° C.

The xylene resin-modified novolak obtained above
100 parts of phenol resin and 13 parts of solid sodium hydroxide were dissolved in 130 parts of water and heated to 50 ° C. with vigorous stirring. To this, 32 parts of epichlorohydrin was mixed with stirring, and while stirring and mixing, the temperature was kept at 80 ° C. and the mixture was uniformly mixed and reacted. After completion of the reaction, excess epichlorohydrin was removed under reduced pressure, benzene was added, and pure water was further added for washing to remove water. Purification was repeated by adding pure water again to wash and remove water. Then,
Benzene was distilled off under reduced pressure to obtain a xylene resin-modified novolak epoxy resin (hereinafter referred to as "resin I") having a melting point of 90 ° C.

Thirty parts of cyanate ester-maleimide resin (BT-2480 manufactured by Mitsubishi Gas Chemical Co., Inc.) was melted at 110 ° C., and synthetic mica (MK-100 manufactured by Coop Chemical Co., Ltd.,
20 parts of an average particle diameter of 4.7 μm) was added and melt mixed. Then, 70 parts of Resin I obtained above was melt-mixed with this mixture, 0.1 part of 2-ethyl-4-methylimidazole was added as a curing catalyst, and the mixture was stirred and mixed at 150 ° C. for 30 minutes.
Heat curing was sequentially carried out at 150 ° C for 30 minutes, 180 ° C for 2 hours, 200 ° C for 2 hours, and 240 ° C for 3 hours. After cooling to room temperature, the cured product was pulverized to obtain resin dust (referred to as dust 1) powder having a particle size of 20 to 100 mesh.

Example 2 Thirty parts of cyanate ester-maleimide resin (BT-2480 manufactured by Mitsubishi Gas Chemical Co., Inc.) was melted at 110 ° C., and hexagonal boron nitride (h-BN) powder (produced by Kawasaki Steel Co., Ltd.) was melted. , HP average particle size
5-15 μm) 20 parts were added and melt mixed. Then, 70 parts of Resin I obtained above was mixed with this mixture, 0.1 part of 2-ethyl-4-methylimidazole was added as a curing catalyst, and the mixture was stirred and mixed at 150 ° C for 30 minutes, and then successively at 150 ° C.
30 minutes, 180 ℃ for 2 hours, 200 ℃ for 2 hours, 240 ℃ for 3 hours
Heat curing for a period of time was performed. After cooling to room temperature, the cured product was pulverized to obtain resin dust (referred to as dust 2) powder having a particle size of 20 to 100 mesh.

Application Example 1 12 parts of hexamine was added to phenol novolac resin, which was crushed by a ball mill and mixed uniformly to obtain a binder resin.
(Denoted as PN). Using this PN, [dust 1 = 1
0; PN = 15; Steel fiber = 25; Rock wool = 20; Aramid fiber = 3; Barium sulfate = 17;
A molding material was prepared with a compounding ratio of graphite = 10] and
After press-molding at 150 ° C. and a pressure of 250 kg / cm ² for 10 minutes, it was taken out of the mold and post-cured in an oven at 200 ° C. for 8 hours to obtain a molded article for friction material.

Application Example 2 To 100 parts of cyanate-maleimide resin (manufactured by Mitsubishi Gas Chemical Co., Inc., BT-2480, powder 100 mesh pass),
As a catalyst, 0.2 part of acetylacetone iron and 0.3 part of dicumyl peroxide were added and uniformly mixed with a Henschel mixer to obtain a binder resin (referred to as BT-248).

Using this BT-248, [dust 2 = 10; BT
-248 = 15; Rock wool = 20; Brass fiber =
8; Aramid fiber = 2; Barium sulfate = 20; Graphite =
5] A molding material was prepared with a compounding ratio of
After press-molding at a pressure of 400 kg / cm ² for 10 minutes, it was taken out of the mold and post-cured in an oven at 230 ° C. for 8 hours to obtain a friction material molded product. With respect to the dusts obtained in Examples 1 and 2, the results of measuring the acetone-soluble content and the heating loss temperature are shown in Table 1 and Table 2, respectively. In addition, application example 1,
Table 3 shows the results of measuring the friction coefficient using the molded product for a friction material obtained in 2.

[0028]

[Table 1]

[0029]

[Table 2] Measurement conditions: room temperature to 700 ° C, heating rate 10 ° C / min, sample amount about 15 mg.

[0030]

[Table 3] Table 3. Friction coefficient Dust 25 ℃ 100 ℃ 150 ℃ 200 ℃ 250 ℃ 300 ℃ 350 ℃ 400 ℃ Application Example 1 1 0.47 0.46 0.45 0.45 0.44 0.43 0.43 0.42 Application Example 2 2 0.48 0.46 0.43 0.43 0.42 0.41 0.41 0.40

From this Table 3, firstly, the resin dust of the present invention maintains substantially the same friction coefficient in a wide temperature range from room temperature to 400 ° C. Further, according to the comparison with the data of heat loss in Table 2, it can be judged that the friction coefficient is substantially the same even at a higher temperature of 450 to 500 ° C., and the effect is extremely serious.

[0032]

As is clear from the detailed description and examples of the invention, the heat-resistant resin dust of the present invention maintains a necessary and sufficient friction coefficient from room temperature to about 400 to 500 ° C. It is extremely meaningful.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08G 73/00 NTB 9285-4J C08L 35/00 LJW 7921-4J 63/00 MKA 8830-4J 79 / 00 LQZ 9285-4J

Claims (5)

[Claims] 1. A novolac type epoxy resin (I) modified with an aromatic hydrocarbon resin, and (a) a monofunctional or polyfunctional cyanate ester, a cyanate ester prepolymer, or a prepolymer of the cyanate ester and an amine. Polymer, or
(a) and (b) a monofunctional or polyfunctional maleimide, a cyanate ester-based curable resin composition (II) and a layered structure containing the maleimide prepolymer or the maleimide and amine prepolymer as a main component Heat-resistant resin dust obtained by compounding the inorganic substance (III), curing at a final curing temperature of 200 ° C or higher, and crushing. 2. The heat-resistant resin dust according to claim 1, wherein the amount of the cyanate-based curable resin composition (II) is 10 to 40% by weight. 3. The compounding amount of the layered inorganic substance (III) is
The heat-resistant resin dust according to claim 1, wherein the total amount of (I) and (II) is 5 to 60 parts by weight with respect to 100 parts by weight. 4. The heat resistant resin dust according to claim 1, wherein the layered inorganic substance (III) is synthetic mica or hexagonal boron nitride. 5. The heat-resistant resin dust according to claim 1, wherein the layered inorganic substance (III) is used as a mixture in which the component (II) is mixed in advance.